Buggy code:
public class OverviewMapFragment extends Fragment implements OnInfoWindowClickListener { private static final String TAG = OverviewMapFragment . class . getSimpleName ( ) ; private GoogleMap mMap ; private InstaMeetService service = null ; private OverviewMapFragment . ServiceListener listener = new OverviewMapFragment . ServiceListener ( ) ; private Map < Marker , SimpleUser > userMarker = new HashMap < Marker , SimpleUser > ( ) ; private Map < Marker , SimpleAppointment > nearAppMarker = new HashMap < Marker , SimpleAppointment > ( ) ; private Map < Marker , SimpleAppointment > myAppMarker = new HashMap < Marker , SimpleAppointment > ( ) ; private Map < Marker , SimpleAppointment > visitingAppMarker = new HashMap < Marker , SimpleAppointment > ( ) ; @ Override public View onCreateView ( LayoutInflater inflater , ViewGroup container , Bundle savedInstanceState ) { } @ Override public void onCreateOptionsMenu ( Menu menu , MenuInflater inflater ) { } @ Override public void onAttach ( Activity activity ) { } @ Override public void onDetach ( ) { } @ Override public void onResume ( ) { } private void setUpMapIfAvailable ( ) { } private void setUpMap ( ) { if ( ( service ) != null ) { Log . i ( OverviewMapFragment . TAG , "Adding<seq2seq4repair_space>markers<seq2seq4repair_space>to<seq2seq4repair_space>map" ) ; getActivity ( ) . runOnUiThread ( new Runnable ( ) { @ Override public void run ( ) { mMap . clear ( ) ; List < SimpleUser > friends = service . getFriends ( ) ; for ( final SimpleUser f : friends ) { Marker mark = mMap . addMarker ( new MarkerOptions ( ) . position ( new LatLng ( f . getLattitude ( ) , f . getLongitude ( ) ) ) . title ( f . getUsername ( ) ) . icon ( BitmapDescriptorFactory . defaultMarker ( HUE_RED ) ) ) ; userMarker . put ( mark , f ) ; } List < SimpleAppointment > hostedApps = service . getMyHostedAppointments ( ) ; for ( final SimpleAppointment a : hostedApps ) { Marker mark = mMap . addMarker ( new MarkerOptions ( ) . position ( new LatLng ( a . getLattitude ( ) , a . getLongitude ( ) ) ) . title ( a . getTitle ( ) ) . icon ( BitmapDescriptorFactory . defaultMarker ( HUE_AZURE ) ) ) ; myAppMarker . put ( mark , a ) ; } List < SimpleAppointment > visitingApps = service . getVisitingAppointments ( ) ; for ( final SimpleAppointment a : visitingApps ) { if ( ! ( hostedApps . contains ( a ) ) ) { Marker mark = mMap . addMarker ( new MarkerOptions ( ) . position ( new LatLng ( a . getLattitude ( ) , a . getLongitude ( ) ) ) . title ( a . getTitle ( ) ) . icon ( BitmapDescriptorFactory . defaultMarker ( HUE_GREEN ) ) ) ; visitingAppMarker . put ( mark , a ) ; } } List < SimpleAppointment > nearApps = service . getNearAppointments ( ) ; for ( final SimpleAppointment a : nearApps ) { <START_BUG> if ( ! ( hostedApps . contains ( a ) ) ) { <END_BUG> Marker mark = mMap . addMarker ( new MarkerOptions ( ) . position ( new LatLng ( a . getLattitude ( ) , a . getLongitude ( ) ) ) . title ( a . getTitle ( ) ) . icon ( BitmapDescriptorFactory . defaultMarker ( HUE_YELLOW ) ) ) ; nearAppMarker . put ( mark , a ) ; } } mMap . setMyLocationEnabled ( true ) ; mMap . moveCamera ( CameraUpdateFactory . newLatLngZoom ( new LatLng ( 52.262948 , 10.521834 ) , 13.0F ) ) ; mMap . setOnInfoWindowClickListener ( OverviewMapFragment . this ) ; } } ) ; } } @ Override public void onInfoWindowClick ( Marker marker ) { } private class ServiceListener extends AbstractInboundMessageListener { @ Override public void listFriends ( ) { } @ Override public void listNearAppointments ( ) { } @ Override public void listVisitingAppointments ( ) { } @ Override public void appointment ( ) { } } private ServiceConnection serviceConnection = new ServiceConnection ( ) { @ Override public void onServiceConnected ( ComponentName className , IBinder binder ) { } @ Override public void onServiceDisconnected ( ComponentName arg0 ) { } } ; }

Fix:
if ( ( ! ( hostedApps . contains ( a ) ) ) && ( ! ( visitingApps . contains ( a ) ) ) ) {